Yamaha Enticer 250 Carb Change

Picked up a ET250 the other day. The Keihin carb pump is dead so I am going to be putting on a Mikuni. Ordered up a vm34 from dennis kirk along with a universal throttle cable part #1920.

What throttle works best with the VM34 mikuni and stock handlebars?

I used the stock throttle lever just had to notch it a little.

if it work that would be good. Setting it all up tomarrow with the 230 mainjet and everything else as it came from DK. Need to remove the factory airbox yet though. Will the uni filter Part #: 305783 mess with the jetting much? I think I will have this thing running long before we get any snow around here

230 may be a little fat i am running 220 with 35 pilot an uni filter same as you need snow to tweak it in

Fat is better than lean I was thinking. Easier to replace a plug than a piston. What is the recommended premix since the injection is being kicked to the curb?

50:1 with premix yamalube is what i have ran all last year.With good clean burn.

Hey guys, not to steal your thread, but it sounds like many of you are kicking your stock carb to the curb. Please take a look at THIS thread and lemme know if any of you would be able to help with this part.

My father has had these sleds for years and were never taken care of so now I am trying to fix them up. I may replace the carbs all together next year but the snow is here. Can you guys help?

And happy new year everyone

Here is my new setup, just have to get the motor back together and mount it up. While I had the engine out to remove the keihin I did a pressure check of the engine. Turned out it had a totally blown clutch side seal. Gave me a chance to freshen up the engine with all new seals and a set of rings and new points. Also yanked off the oil injection pump since that won't be needed anymore. I may have my old carb setup for sale after I get it running on the mikuni good there magiccow. I know I seen somewhere how to setup the points and timing but can't find it again....anyone know where that is for my 78 et250? Think I will have this thing running long before we get any snow here in eastern S Dakota.

Anyone know how to set up the points on this et250? There is a timing mark but I don't know if its tdc or what?? I set the points at .016" with it at the timing marks in the picture. Is that all there is to it? I know I saw the specs somewhere but didn't bookmark it and can't find them back. Took a picture of it somewhat together with it at the timing marks.

I just swapped out the Keihin for a 34mm Mik in my 1980 250 ET this weekend, sled runs great, has more pep, and is smoother all the way thru the power band. I would do this swap even if the Keihin was working good, the Mikuni makes a big difference in performance. You will also have to unhook the oil injection and run pre mix. Not saying there is anything wrong with the oil injection units in these sled, I just do it on all mine as a precautionary measure.
If anybody is looking swap out their Keihin for a Mik, this is what I used to start with.....

34mm Mikuni VM
220 main jet
50 pilot jet
DK part #1920 universal Mikuni throttle cable
DK part #1928 choke cable
DK part#1926 Mikuni choke conversion

I had a Mik 34mm carb flange already but had to modify the mounting holes to fit the bolt pattern and cut some spacers to bolt it down. DO NOT remove the stock angled mounting spacer, you will need that angle for the carb to clear the steering post. I also had to notch the stock throttle to get the slide to close fully. I also took one of the mounting bolts out of the gas tank and used a longer one and a spacer to mount the fuel pump. This jetting was very close to being spot on in 25 degree weather....I'm not going to mess with it unless it gets a lot warmer.



This mofo is oval ready

Hope this helps

autotech57103 said:

Anyone know how to set up the points on this et250? There is a timing mark but I don't know if its tdc or what?? I set the points at .016" with it at the timing marks in the picture. Is that all there is to it? I know I saw the specs somewhere but didn't bookmark it and can't find them back. Took a picture of it somewhat together with it at the timing marks.

Click to expand...

This may be what you were looking for......


http://www.totallyamaha.net/forums/showthread.php?t=82332

Mikuni VM-34 on ET-340 engine ??

northern srx said:

Anyone got any info on doing this Mikuni VM-34 upgrade on the ET-340 engine ?

Click to expand...

DYsLeXiC said:

That is an interesting idea....
Hmmmmmmmmmm....
my ET-340 could use some attention....

Click to expand...

2ooosrx said:

We have done this with our ET-340 aswell.

Click to expand...

I have put a Mikuni VM-34 carb on my ET-340 engine
but I like to compare my jetting set up to what others have found working.
















I left the heat shield in place from the old carb,
but I do not think it is necessary.

Keep up the good work guys... this forum is super-interesting for amateurs like me trying to keep my old Enticers alive and running... been dealing with carb issues on my 250 for awhile now and now I cant wait to try this fix. Thanks to everyone for your input here. Really helps.

Anyone have a kimpex, Gamma or Royal Distributing # for the carb flange can't get one from dennis Kirk by thursday.

SxViperSman said:

Anyone have a Kimpex part # for the carb flange ?

Click to expand...

Kimpex part # 07-100-13
( For the Mikuni VM-32/34 carb. )

thanks

RJH...By inlet valve you mean needle jet? The needle that slides with the throttle cable and has 5 notches for the clip? Bear with me here, I am used to my 4-stroke and EFI. I t has been a looong time since working with carbs.

Mikuni carb language

RJH...By inlet valve you mean jet needle? The needle that slides with the throttle cable and has 5 notches for the clip? Bear with me here, I am used to my 4-stroke and EFI. I t has been a looong time since working with carbs.

Ok, so my friend called me up today and he said his 1981 ET250 was no longer starting up. It has nice blue fat spark, but we put a new plug in, and no gas ever touches the plug end after trying to start with the choke. Compression is 130, and I replaced all the fuel lines last year. I went over all the tubing today and it was all good. Pulse tube looks good, no cracks. I cleaned the whole carb inside out again, diaphrams on the ol' butterfly keihin were curly but didn't look like they had any cracks. It was a bit dirty in there but not any dirtier than what I have previously seen. The sled is stock and looks good.

So, I decided we would replaced as you guys have suggested here,
Im in Canada, so all the parts Im quoting are royal-distributing part numbers, except the Dennis Kirk Vm34 carb which is part# 1655

VM34 Flange: 07-100-13 (Thanks to whoever posted that )
Univ. Throttle Cable: 05-138
Fuel Pump: 07-187-01 (Single output)
Uni Black Air filter: 07-298
Choke Conversion kit: 07-185 (Cuz someone said the stock cable would work - we shall see)
220 Main jet

The VM34 from Dennis Kirk is configured as follows:

Spigot OD: 40 mm
Bell OD: 58 mm
Main Jet: 330
Pilot Jet: 30
Air Jet: 0.5
Needle Jet: 159 Q-2
Jet Needle: 6DH2
Throttle Slide: 2.5

But there was another Vm34 (Part #16465) that was configured with a couple differences, they were:

Main Jet: 260
Pilot Jet: 35
Air Jet: 2.0
Jet Needle: 6DH4

I know what the pilot and main jets do, but I don't really understand the air jet all too well, it somehow does something in the 1/2 to full open throttle ranges - exactly like the main jet does, but it also gives air to the pilot system through the pilot air screw. So, when I swap out the carb will I need to change the air jet?

I'm also worried about the needle and needle jet, the one that is shipping on the carb I bought is a 6DH2, whereas there was metion that the 6DH4 and needle jet O-0 (Does anyone have the ###)might be the way to go... I suppose testing will be in order.

Im at about 50ft above sea level. Temperatures range from 0 to -30C.

Thanks to everyone here, and anyone who can provide a bit more information about the air jet,

Before doing all those changes. Have you tried bypassing the fuel shutoff on the side of the fuel tank?
Mine gave me the same scenario. I bypassed the shutoff valve
& it fired right up.
Let me know how you make out
Hoss
Orangeville, Ontario